This invention relates to managing data in a distributed storage system storing data across a plurality of devices in general and more specifically to managing data when one or more virtual devices are removed from a storage pool comprising a plurality of virtual devices.
Storage systems often distribute data across multiple storage devices. Use of multiple storage devices allows the storage system to scale when the amount of storage space required increases. Furthermore, data can be replicated across multiple storage devices to provide fault tolerance. However, management of data distributed across multiple storage devices is more complicated than data stored on a single device. Enterprises that store a large amount of data using such distributed system assign a system administrator or a database administrator to manage the storage systems of the enterprise. System administrators typically assign storage devices or portions of storage devices for specific purposes. For example, a set of storage devices may be used for development related activities, another set of storage devices may be used for testing, and another set of storage devices may be used for production.
A system administrator may over-estimate or under-estimate the amount of storage required for a particular purpose. If the system administrator over estimates the amount of storage used for a particular purpose, the system administrator may repurpose a storage devices for another purpose. System administrators may repurpose storage devices for other reasons, for example, if a new project is started, resources from existing projects may be used for the new project. If a storage device being used for a purpose is repurposed, the data stored on the storage device is moved out of the storage device. However, other storage devices may store references to data stored on this device. These references become outdated when the data referred to by them is moved. As a result, moving data from storage devices leads to inefficiencies that are not adequately addressed by conventional techniques.